Air-cooled gas lasers and associated systems and methods

ABSTRACT

Embodiments of an air-cooled gas laser are disclosed herein. A laser configured in accordance with one embodiment includes a laser superstructure, an optical assembly, and an elongated thermal decoupler member having a first end portion fixedly coupled to the optical assembly and a second end portion fixedly coupled to the laser superstructure. The laser further includes an optical assembly that includes a first holder member fixedly coupled to the first end portion of the thermal decoupler, a second holder member pivotally coupled to the first holder member and fixedly coupled to the laser superstructure, and a flexible seal having a portion coupled to the laser structure and disposed at least between the first holder member and the second holder member.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationNos. 61/944,010, filed Feb. 24, 2014; 61/944,007, filed Feb. 24, 2014;and 61/943,995, filed Feb. 24, 2014, all which are incorporated hereinby reference in their entireties.

TECHNICAL FIELD

The present disclosure is directed generally to gas lasers and, morespecifically, to air-cooled gas lasers, including high power air-cooledlasers.

BACKGROUND

Carbon dioxide (“CO₂”) lasers have a variety of industrial uses,including material processing. For example, a CO₂ laser can cut shapesor profiles out of materials, remove or modify surface layers ofmaterials, and weld or sinter materials. A CO₂ laser typically has asealed resonator structure containing a laser cavity filled with aprocess gas. The laser cavity houses electrodes configured to coupleelectromagnetic energy into the process gas to excite a plasma. Ingeneral, the output power level of a CO₂ laser is inversely proportionalto the process gas plasma temperature; as the process gas temperatureincreases, the laser output declines proportionately. Thus, an effectivesolution for heat removal from the laser superstructure is paramount toachieving optimum laser power output. CO₂ lasers typically operate atefficiencies of less than 15%, making thermal management one of the keydesign challenges for effective CO₂ laser operation.

In some CO₂ laser designs, liquid cooling schemes are employed to removeheat from the laser cavity. In a liquid cooling scheme, a heat exchanger(e.g., a refrigerated chiller) removes heat by pumping a liquid coolantthrough the electrodes and/or the laser superstructure. One disadvantageof liquid cooling is that it increases the complexity of a laser and thecost of ownership. Other CO₂ lasers employ an air cooling scheme. In anair cooling scheme, heat from the plasma is transferred into theelectrodes. The electrodes transfer heat into the outer walls of thelaser superstructure, where a high-surface-area structure with forcedair flow removes the heat from the resonator structure. Although aircooling is less complicated than liquid cooling, it is not as efficient.Thus, air-cooled CO₂ lasers typically have a greater power output sag astheir temperature tends to increase more during operation than theirwater-cooled counterparts. Due to these limitations, at this time themaximum output power produced by air-cooled CO₂ lasers does not exceed100 W.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an isometric view and FIG. 1B is an enlarged,partially-exploded isometric view of a gas laser configured inaccordance with an embodiment of the present technology.

FIG. 1C is a partially-exploded isometric view showing an opticalassembly of the laser of FIGS. 1A and 1C in more detail.

FIG. 2 is a cross-sectional view of the laser of FIGS. 1A and 1B.

FIG. 3A is a top plan view of a laser superstructure of the laser ofFIGS. 1A and 1B in a contracted state in accordance with an embodimentof the present technology.

FIG. 3B is a top plan view of the laser superstructure in an expandedstate in accordance with an embodiment of the present technology.

FIG. 4 is a partially exploded view showing a portion of the opticalassembly in more detail.

FIG. 5 is a partially exploded view showing an electrode assembly of thelaser in more detail.

FIG. 6A is an isometric view and FIG. 6B is a partially-explodedisometric view showing a resonator optics assembly of the laser in moredetail.

DETAILED DESCRIPTION

The following disclosure describes various types of gas lasers andassociated systems and methods for improving various aspects of theirperformance. For example, in at least some embodiments, an air-cooledgas laser can include structures and features that reduce operatingtemperatures and improve output power. As discussed above, traditionalair-cooled gas lasers typically have greater power output sag thanliquid-cooled gas lasers because air-cooled lasers are less effective atremoving heat and tend to operate at higher gas plasma temperatures.Another challenge with air-cooled lasers is that their higher operatingtemperatures cause thermal expansion during laser operation. Thermalexpansion can impact a gas laser's performance in several ways. Forexample, expansion of the laser superstructure can alter the laser'soutput wavelength and lower output power and affect mode shape byincreasing the separation distance between the laser's resonator optics.Asymmetric thermal expansion of the resonator structure can furtherreduce the laser output power and mode shape by causing the lasersuperstructure to bend or twist. Such expansion generally occurs becauseof structural and thermal asymmetries in the resonator structure.

In at least some gas lasers, components within the resonator structure(e.g., the electrodes and the resonator optics) can thermally expand.Expansion in the resonator optics can cause misalignment of the laserresonator which can result in lowered power output and mode shape. In atleast some instances, thermal expansion can be exacerbated when theresonator optics absorb non-reflected beam energy. For at least thesereasons, there is a need for technology that reduces the effects ofthermal expansion in gas lasers. There is also a need for technologythat improves heat transfer in gas lasers to achieve higher operatingpowers without debilitating levels of output power sag during operation.

Systems, devices, and methods configured in accordance with embodimentsof the present technology can at least partially address one or more ofthe problems described above and/or other problems associated withconventional technologies whether or not stated herein. For example, agas laser configured in accordance with at least some embodiments of thepresent technology can include a thermally decoupled lasersuperstructure. Such a decoupling allows the laser superstructure tothermally expand/contract without substantially impacting the separationdistance between the laser's resonator optics. In another embodiment, agas laser configured in accordance with the present technology includesan optical assembly with the ability to pivot and thereby compensate forany bending of the laser superstructure caused by thermal expansion. Inadditional or alternate embodiments, a gas laser can include anelectrode assembly having an electrode biasedly coupled to a frame toimprove heat transfer into the laser superstructure. In still furtherembodiments, a gas laser can include a resonator optics assemblyconfigured to remove heat from an optical element, such as heatassociated with non-reflected laser beam energy.

Certain details are set forth in the following description and FIGS.1A-6B to provide a thorough understanding of various embodiments of thedisclosure. Other details describing well-known structures and systemsoften associated with CO₂ lasers, however, are not set forth below toavoid unnecessarily obscuring the description of the various embodimentsof the disclosure. Many of the details and features shown in the Figuresare merely illustrative of particular embodiments of the disclosure.Accordingly, other embodiments can have other details and featureswithout departing from the spirit and scope of the present disclosure.In addition, those of ordinary skill in the art will understand thatfurther embodiments can be practiced without several of the detailsdescribed below. Furthermore, various embodiments of the disclosure caninclude structures other than those illustrated in the Figures and areexpressly not limited to the structures shown in the Figures. Moreover,the various elements and features illustrated in the Figures may not bedrawn to scale.

In the Figures, identical reference numbers identify identical or atleast generally similar elements. To facilitate the discussion of anyparticular element, the most significant digit or digits of anyreference number refer to the Figure in which that element is firstintroduced. For example, element 110 is first introduced and discussedwith reference to FIG. 1A.

Laser Overview

FIG. 1A is an isometric view and FIG. 1B is an enlarged,partially-exploded isometric view of a gas laser (“laser 100”), such asa CO₂ laser, configured in accordance with an embodiment of the presenttechnology. Although not shown for purposes of clarity, the laser 100can include other structures and features not shown in the illustratedembodiment, such as a gas source (e.g., a CO₂ gas source), a controller,an internal fan, etc. Referring to FIGS. 1A and 1B together, the laser100 includes a laser superstructure 110 at least partially containedwithin a housing 102. The laser superstructure 110 has a cavity 113(FIG. 1B) extending from a first side 115 a to a second side 115 b alongthe long axis of the laser superstructure 110. A first optical assembly140 a is disposed at the first side 115 a and faces a second opticalassembly 140 b (collectively “optical assemblies 140”) disposed at thesecond side 115 b. The first optical assembly 140 a can include anoptical adjustment structure 144 operably coupled to a resonator opticsassembly (not visible in FIG. 1A) at an opposite side of the firstoptical assembly. The optical adjustment structure 144 can include, forexample, adjustment features 146 (e.g., adjustment knobs, dials, screws,etc.) for fine-tune adjustment of the laser's resonator optics. In atleast some embodiments, the second optical assembly 140 b can includeoptical components similar in structure and/or function to the firstoptical assembly 140 a.

In the illustrated embodiment, the laser 100 includes a one or moreelongated thermal decoupler members 117 (e.g., elongated rods) atopposite sides of the laser superstructure 110 and extending along itslong axis. Each of the decoupler members 117 includes a first endportion 119 a and a second end portion 119 b fixedly coupled to thefirst optical assembly 140 a and the second optical assembly 140 b,respectively. In the illustrated embodiment, the decoupler members 117are coupled to either of the optical assemblies 140 using integral shaftcollars 118, although in other embodiments other attachment techniquescan be used (e.g., welding or via fasteners). As best seen in FIG. 1B,the decoupler members 117 are in parallel with one another and arrangedin two pairs at opposite side sides of the laser superstructure 110. Inalternate embodiments, the decoupler members 117 can be arrangeddifferently (e.g., at the top and bottom sides of the laser 100). Thelaser 100 can also include a different number of decoupler members thanshown in the illustrated embodiments (e.g., one decoupler member at eachside of the laser 100). Further, the decoupler members can havedifferent sizes and/or shapes than shown in the illustrated embodiments,including non-cylindrical shapes (e.g., a rectangular-shaped tube orplate). In one embodiment a decoupler member can have a hollow interior.

The decoupler members 117 can be formed from fabricated metal or othersuitably rigid materials, and the laser superstructure 110 can be formedfrom fabricated laser-compatible materials, such as aluminum. In oneembodiment, for example, the decoupler members 117 are formed fromnickel/iron alloys (e.g., FeNi42 or FeNiCo alloys) having a coefficientof thermal expansion (CTE) that is relatively smaller than the CTE ofthe laser superstructure 110. For example, the decoupler members can befabricated from Invar, Inovco, Elinvar, and/or Sitall, which have asubstantially lower CTE than the CTE of aluminum. Accordingly, thevolumetric thermal expansion of the decoupler members 117 can besubstantially less than the volumetric thermal expansion of the lasersuperstructure 110. As further shown in FIGS. 1A and 1B, a thermalinsulator 116 (e.g., a ceramic spacer) can be disposed between thedecoupler members 117 and sidewall surfaces 112 of the lasersuperstructure 110. The thermal insulator 116 can thermally isolate thedecoupler members 117 from the laser superstructure 110. In additionalor alternate embodiments, the decoupler members 117 can be thermallyisolated from the sidewall surfaces 112 by forming a gap (not shown)between the decoupler members 117 and the sidewall surfaces 112. Asdescribed in greater detail below, the relatively lower CTE and/orthermal isolation of the decoupler members 117 can thermally decouplethe optical assemblies 140 from the resonator structure 110, which, inturn, increases beam path stability between the optical assemblies 140.

With reference still to FIG. 1B, the laser superstructure 110 isconfigured to slidably receive a removable electrode assembly 170 withinthe cavity 113 through an opening 114 at the first side 115 a. Theelectrode assembly 170 includes a frame 172 (e.g., an electrode cage)carrying a first electrode 173 a (or electrode array) and a secondelectrode 173 b (or electrode array) facing the first electrode 173 a(collectively “electrodes 173”). The electrodes 173 are operably coupledto an energy source 175 (shown schematically), such as an RF energysource, configured to energize the electrodes 173 and excite a plasmatherebetween. The laser superstructure's opening 114 is sealed by thefirst optical assembly 140 a and an extension member 126 (e.g., metalextension) located between the first optical assembly 140 a and a flange122 surrounding the perimeter of the opening 114. For example, eitherside of the extension member 126 can be welded, clamped, fastened,adhered, and/or otherwise coupled to the flange 122 and first opticalassembly 140 a to form a tight seal for holding a low pressure or vacuumin the cavity 113.

FIG. 1C is a partially-exploded isometric view showing the first opticalassembly 140 a in more detail. As shown, the first optical assembly 140a includes first and second holder members or first and seconds plates150 a and 150 b, respectively, and a resonator optics assembly 142(“resonator optics 142”). As shown, the second plate 150 b is disposedbetween resonator optics 142 and the first plate 150 a and pivotallycoupled to the first plate 150 a via a plurality of rotational joints153. As described in greater detail below, the rotational joints 153enable the second plate 150 b to pivot relative to the first plate 150 afor mechanically stabilizing the resonator optics 142 to maintainoptical alignment when the laser superstructure 110 bends, twists,warps, or otherwise deforms due to thermal expansion.

In the illustrated embodiment, the first plate 150 a includes a firstaperture 103, the second plate 150 b includes a second aperture 105, andthe adjustment structure 144 includes a linkage having linkages elements121 a and 121 b that extend through first and second apertures 103 and105 to operably couple the adjustment structure 144 to the resonatoroptics 142. As further shown in FIG. 1C, a flexible seal assembly 120(“flexible seal 120”) extends through the first aperture 103 and isseated on an inner shelf 107 within the second aperture 105. In theillustrated embodiment, the flexible seal 120 includes a bellows 123(e.g., stainless steel bellows) having an outer flange 104 a and aninner flange 104 b. The flexible seal 120 further includes a first sealmember 124 a (e.g., an O-ring) disposed between the adjustment structure144 and the outer flange 104 a, and a second seal member 124 b (e.g.,another O-ring) is disposed between the inner flange 104 b and the innershelf 107. As described in greater detail below with reference to FIGS.2A and 2B, the flexible seal 120 is configured to maintain the lowpressure seal of the cavity 113 by expanding and contracting toaccommodate thermal expansion and contraction of the lasersuperstructure 100. In at least some embodiment, the flexible seal 120can include other types of stretchable/compressible members in additionto or in lieu of a bellows, such as a stretchable/compressible gasket(e.g., a stretchable/compressible O-ring) or an accordion-pleated seal.

FIG. 2 is a cross-sectional view of the laser 100 taken along line 2-2of FIG. 1A. As shown, the laser 100 includes a plurality of heatdistributors 203 attached to lower and upper outer surface surfaces 225a and 225 b of the laser superstructure 110 and extending along its longaxis. The heat distributors 203 project outwardly from surfaces 225 aand 225 b and collectively form a large surface area through which thelaser superstructure 110 can transfer heat into the ambient environment.In one embodiment, the laser 100 can include an air mover (not shown),such as a fan, configured to move air axially through the heatdistributors 203 and to increase the rate of heat transfer through thewalls of the laser superstructure 100. The heat distributors 203 canhave a geometry and/or density optimized to a performance curveassociated with the air mover. In one embodiment, the heat distributors203 can be formed from folded or corrugated sheet metal, and the heatdistributors 203 can be welded, bonded, or otherwise coupled to thelower and uppers surfaces 225 a and 225 b. In other embodiments,however, the heat distributors 203 may be composed of differentmaterials and/or have a different arrangement.

As further shown in FIG. 2, the laser superstructure 110 includes agenerally planar lower member 230 a and a U-shaped upper member 230 b.The lower member 230 a is joined to outer sidewall portions 233 of theupper member 230 b, and the lower member 230 a includes a raised firstbase portion 235 a facing a corresponding second base portion 235 b ofthe upper member 230 b (collectively “base portions 235”). Each of thebase portions 235 has an inner surface 237 that contacts the electrodeassembly's frame 172 and side surfaces 239 that cooperate with ridges277 projecting outwardly from the frame 172.

The upper member 230 b includes flexible wall portions 232 extendinglaterally from the second base portion 235 b and toward the outersidewalls 233. In use, the flexible walls 232 enable the lasersuperstructure 110 to expand when the electrode assembly 170 is pushedinto the cavity 113 through the opening 114 (FIG. 1B). The flexiblewalls 232 can collapse the laser superstructure 110 onto the electrodeassembly 170 when it is fully installed in the cavity 113 and properlyseated on the base portions 235. In one embodiment, the lasersuperstructure 110 can have a configuration that enables it to expandand collapse in a manner similar to that described in U.S. Pat. No.6,983,001, filed Dec. 16, 2002, and titled “Laser with Heat TransferSystem,” which is incorporated herein by reference in its entirety.

In the illustrated embodiment, the lower and upper members 230 a and 230b are fabricated separately (e.g., via metal extrusion) and then joinedtogether to form a continuous structure. For example, the outersidewalls 233 can be joined to a surface of the lower member 230 a,using, e.g., brazing, welding, or suitable other attachment techniques.In an alternate embodiment, the lower member 230 a can include sidewallportions 234 (shown in hidden lines) extending toward the upper member230 b and located between the outer sidewalls 233.

One advantage of forming the lower and upper members 230 a and 230 bseparately is that it enables the various features (e.g., the baseportions 235, the flexible walls 232, etc.) to be defined in the members230 a and 230 b using high-precision fabrication processes, such asmilling, laser cutting, or mechanical polishing. For example, in oneembodiment, the laser superstructure's inner surfaces 237 can bepolished to reduce surface topography. In one aspect of this embodiment,the polished surfaces can increase thermal transfer between the lasersuperstructure 110 and the electrode assembly 170. In an additional oralternate embodiment, the base portions 235, the flexible walls 232, andother features of the laser superstructure 110 can be milled, laser-cut,or otherwise defined in either of the inner surfaces 237 and/or othersurfaces of the laser superstructure 110. In at least some embodiments,these features can be formed with tight dimensional tolerances toimprove heat distribution and thermal uniformity (i.e., thermalsymmetry).

Thermal Decoupling

As noted above, the decoupler members 117 can thermally decouple theoptical assemblies 140 from the laser superstructure 110 to preventthermal expansion and contraction of the laser superstructure 110 fromaffecting the resonator mirror spacing. FIG. 3A is a top plan view ofthe laser superstructure 110 in a contracted state (e.g., a non-expandedstate or a less expanded state) in accordance with an embodiment of thepresent technology. As shown, the laser superstructure 110 is at a firsttemperature level, T₁, and the laser superstructure 110 has a firstlength L₁ along the long axis, the decoupler members 117 each have alength L_(S), and the resonator optical assemblies 140 define aresonator optics spacing of length L_(B). In one embodiment, the lasersuperstructure 110 is at the first temperature level T₁ when the laser100 is an off state. For example, in one embodiment the firsttemperature level T₁ can be a room temperature level. Alternately, thelaser superstructure 110 can be at the first temperature level T₁ whenthe laser 100 is in a cool down phase or when it is operating at lowpower.

FIG. 3B is a top plan view of the laser superstructure 110 in anexpanded state in accordance with an embodiment of the presenttechnology. As shown, the laser superstructure 110 has been heated fromthe first temperature level T₁ to a second temperature level, T₂. Thelaser superstructure 110 can be at the second temperature level T₂, forexample, when the laser 100 is operating at high power and transferringa substantial amount of heat into the body of the laser superstructure110. In the illustrated embodiment, the increased heat has caused thelaser superstructure 110 to expand from the first length L₁ to a secondlength L₂. The decoupler members 117, however, have not substantiallyexpanded. As discussed above, the decoupler members 117 can have a lowCTE and/or they can be thermally isolated from the laser superstructure110. As a result, the decoupler member length L_(S) generally does notchange when the laser superstructure 110 is heated to the elevatedtemperature T₂ thereby stabilizing the resonator optics spacing L_(B).Likewise, the length of the beam path L_(B) does not change since theresonator optical assemblies 140 are fixedly coupled to the decouplermembers 117. As further shown in FIG. 3B, the laser superstructure 110has forced the flexible seal 120 towards the first plate 150 a, and theflexible seal 120 has been compressed between the first and secondplates 150 a and 150 b (as shown by the arrows). Because the flexibleseal 120 is compressible, the expansion of the laser superstructure 110does not rupture the seal 120 and the cavity 113 maintains its sealintegrity.

Optical Assembly

As discussed above, the first optical assembly 140 a can have theability compensate for any bending of the laser superstructure 110caused by thermal expansion. In some instances, the bending of the lasersuperstructure 110 can force (e.g., push/pull) the decoupler members 117in the Z-axis directions, which in turn produces forces that causemovement or shifting of the first optical assembly 140 a relative to thelaser superstructure 110. If uncorrected, such movement or shiftingmight ultimately affect the alignment of the optical assemblies 140and/or the beam path therebetween. As described below, the first opticalassembly 140 a is configured to decouple the resonator optics 142 (FIG.1C) from the laser superstructure 110 in a way that prevents bending,twisting, warping or other types of laser superstructure deformationfrom causing misalignment between the optical assemblies 140.

FIG. 4 is an enlarged isometric view showing the first plate 150 a andthe second plate 150 b of the first optical assembly 140 a in moredetail. As shown, the first plate 150 a is fixedly coupled to thedecoupler members 117 and pivotally coupled to the second 150 b by therotational joints 153, which are located at the top, bottom, left, andright sides of each of the plates. Each of the rotational joints 153includes a pivot element or pivot pin 455 slidably received in acorresponding receptacle 457. The pivot pins 455 on the first plate 150a are aligned to the horizontal center line Hc, and the pivot pins 455on the second plate 150 b are aligned to the vertical center line Vc.

The second plate 150 b is fixedly coupled to the flexible seal 120 (FIG.1B) and carries a portion of the laser's resonator optics (not visiblein FIG. 4) at rearward facing side 407. The second plate 150 b includesleft and right edge portions 429 a and 429 b. The left and right edgeportions 429 a and 429 b have cut-out regions 427 (shown in hiddenlines) through which each pair of decoupler members 117 extend to engagethe first plate 150 a without contacting the second plate 150 b and thecorresponding rotational joint 153 located therebetween.

In operation, the second plate 150 b holds a steady beam path bymaintaining alignment of the laser's resonator optics across the cavity113 (FIG. 1B), and the second plate 150 b pivots relative to the firstplate 150 a to isolate resonator optics 142 (FIG. 1C) from the effectsof asymmetric thermal expansion of the laser superstructure 110. Morespecifically, the second plate 150 b rotates about the X- and/or Y-axisin response to Z-axis movement of laser superstructure 110. For example,when the left and right sides of the laser superstructure 110 force thesecond plate 150 b in opposite Z-axis directions, the top and bottomrotational joints 153 enable the second plate 150 b to pivot about thevertical center line Vc in the clockwise or counterclockwise direction.When the upper and lower sides of laser superstructure 110 force thesecond plate 150 b in opposite Z-axis directions, the left and rightrotational joints 153 enable the second plate 150 b to pivot about thehorizontal center line Hc in the clockwise or counterclockwisedirection. In one aspect of this embodiment, the rotational joints 153generally provide only two degrees of freedom (i.e., about the verticaland horizontal center lines), and therefore the first and second plates150 a and 150 b are not free to translate in the X-Y plane nor are theyfree to rotate about the Z-axis.

Electrode Assembly

In at least some embodiments, the electrode assembly 170 can beconfigured to improve heat transfer through the laser superstructure 110and into the ambient. FIG. 5 is a partially exploded view showing theelectrode assembly 170 in more detail. The frame 172, for example,includes a first frame member 580 a and a second frame member 580 b(collectively “frame members 580”) seated on outer wall portions 582 ofthe first frame member 580 a. Individual frame members 580 include acentral wall portion 583 having an outer surface 586 configured toengage either of the laser superstructure's inner surfaces 237 (FIG. 2).The central wall portion 583 is integrally formed with the outer wallportions 582, and the wall portions 582 and 583 together define aninterior cavity 579 containing one of the electrodes 173. Each of theelectrodes 173 is electrically isolated from the frame 172 by adielectric spacer 587 located between the frame 172 and either of theelectrodes 173. The dielectric spacer 587 can include, for example, analuminum oxide plate.

As further shown in FIG. 5, a plurality of arrayed first openings 584extend through the central wall portion 583 of the first frame member580 a, a plurality of arrayed second openings 585 extend through theunderlying dielectric spacer 587, and a plurality of threaded holes 593extend into a backside surface 591 of the first electrode 173 a. Each ofthe threaded holes 593 is configured to receive a first end portion 592a of a fastener 590 (e.g., a shoulder screw) inserted through one of thefirst openings 584 and a corresponding one of the second openings 585.Each of the first openings 584 is surrounded by an individual depression594, and the depression 594 is positioned to receive a dielectricelement 595 and a biasing element 597 held in place by a second endportion 592 b of the fastener 590. In one embodiment, the dielectricelement 595 is a ceramic washer and the biasing element 597 is abelleville washer. In other embodiments, however, other types ofinsulator and/or biasing elements can be used. In an additional oralternate embodiment, the fastener 590 can have an electricallyinsulative coating.

In use, each fastener 590 and corresponding biasing element 597 firmlyholds a portion of the frame member 580 a, the underlying dielectricspacer 587, and the underlying electrode 173 in surface-to-surfacecontact. More specifically, the spring force of the biasing element 597biases the fastener's second end portion 592 b away from the first framemember 580 a. When forced away from the first frame member 580 a, thefastener 590 pulls the underlying electrode 173 a into full contact withthe spacer 587 and the spacer 587 into full contact with the interiorside of the corresponding central wall portion 583 of the frame member580.

In one aspect of this embodiment, the fastener 590 and the biasingelement 597 help reduce thermal resistance through the electrodeassembly 170 by closing localized gaps between the electrode 173 a andthe spacer 587 and between the spacer 587 and the first frame member 580a. In some instances, a gap may form during thermal expansion because ofasymmetries in the geometry and/or the materials of the frame member 580a, the spacer 587, and/or the electrode 173 a. In at least someembodiments, the spring force of the biasing element 597 can be selectedto suitably close the gap, yet prevent spring forces from accumulatingwithin the electrode 173 a and the spacer 587 during thermal expansion.Although not shown in FIG. 5 for purposes of clarity, similar fastenersand biasing elements can be used to hold the second frame member 580 b,the corresponding spacer 587, and the second electrode 173 b insurface-to-surface contact with one another.

Resonator Optics Assembly

The laser 100 can also be configured to reduce the effects of thermalexpansion at the optical assemblies 140 by sinking localized heatabsorbed into the optics (e.g., heat associated with non-reflected beamenergy). FIG. 6A is an isometric view and FIG. 6B is apartially-exploded isometric view showing the resonator optics 142 inmore detail. The resonator optics 142 are configured to carry andposition the optical element 648 (e.g., a mirror) within the lasercavity 113. As described below, the resonator optics 142 are alsoconfigured to sink heat from the optical element 648 during operation ofthe laser 100.

As shown in FIG. 6A, the resonator optics includes a carrier member 662(“carrier 662”) having a raised upper portion 664 a and a raised lowerportion 664 b (collectively “raised portions 664”). A first heat sinkelement 649 a is adjacent the upper portion 664 a, a second heat sinkelement 649 b is adjacent the lower portion 664 b, and the opticalelement 648 is sandwiched between the first and second heat sinkelements 649 a and 649 b (“collectively heat sink elements 649”) andheld against the carrier 662 by first biasing elements 652 (e.g., springfingers) extending downwardly from either of the raised portions 664.

Referring to FIG. 6B, each of the raised portions 664 includes anaperture 668 facing an adjacent heat sink element 649 and containing asecond biasing element 654 (e.g., a compression spring). The secondbiasing element 654 extends outside of the aperture 668 and ispositioned to engage an outer side surface 661 of an adjacent heat sinkelement 649. Each of the heat sink elements 649 has an inner sidesurface 663 that engages a corresponding side surface 642 of the opticalelement 648. The heat sink elements 649 include openings 665 configuredto receive fasteners 647, and the fasteners 647 extend through theopenings 665 to couple the heat sink elements 649 to the carrier 662.The openings 665 are surrounded by a surface depression 667 configuredto receive a third biasing element 641 (e.g., a belleville washer), andthe third biasing element 641 is held within the depression 667 by anend portion 674 of the fastener 647. The optical element 648 has abackside surface 643 and a surface feature 645 formed therein and biasedinto engagement with a retainment element 658 (e.g., a rod or pin) viathe first biasing elements 652 (FIG. 6A). The retainment element 658 islocated in a channel 651 extending vertically through a forward facingsurface 669 of the carrier 662. The retainment element 658 is configuredto be inserted into the channel 651 through a hole 659 in the upperportion 664 a of the carrier 662.

In operation, the carrier member transfers heat away from the opticalelement 648 through its backside surface 643 and its sides surfaces 642.The first biasing elements 652 enhance heat transfer through thebackside surface 643 by urging the optical element 648 against thecarrier's forward facing surface 669 and by maintainingsurface-to-surface contact therebetween. The first biasing elements 652also hold the surface feature 645 and the retainment element 658 inengagement with one another. In one aspect of this embodiment, theretainment element 658 keeps the optical element 648 from moving in thelateral direction along its long axis. For example, the retainmentelement 658 can prevent the optical element 648 from shifting duringthermal expansion and/or when transporting the laser 100.

The heat sink elements 649 facilitate heat transfer through the sidesurfaces 642 of the optical element 648. The second biasing elements 654further enhance heat transfer at the side surfaces 642 by urging theheat sink elements 649 against the optical element 648 and bymaintaining surface-to-surface contact therebetween. Referring to FIG.6A, the second biasing elements 654 also maintain a gap G₁ between theheat sink elements 649 and either of the outer portions 664. The gap G₁provides a space into which the heat sink elements 649 can thermallyexpand. In one aspect of this embodiment, the gap G₁ can prevent stressconcentrations from forming within the heat sink elements 649 and/or theoptical element 648 during thermal expansion. Similar to the secondbiasing elements 654, the third biasing elements 641 can have a springforce selected to bias the heat sink elements 649 against the carrier662 yet still allow the heat sink elements 649 to expand outwardly.

From the foregoing, it will be appreciated that specific embodiments ofthe disclosure have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the various embodiments of the present technology.Moreover, because many of the basic structures and functions of laserapparatus are known, they have not been shown or described in furtherdetail to avoid unnecessarily obscuring the described embodiments.Further, while various advantages and features associated with certainembodiments of the disclosure have been described above in the contextof those embodiments, other embodiments may also exhibit such advantagesand/or features, and not all embodiments need necessarily exhibit suchadvantages and/or features to fall within the scope of the disclosure.

I/we claim:
 1. A laser, comprising: a laser superstructure having a first side and a second side opposite the first side; an elongated thermal decoupler member having a first end portion and a second end portion, wherein the second end portion is fixedly coupled to the laser superstructure proximate; and an optical assembly, including— a first holder member fixedly coupled to the first end portion of the thermal decoupler, a second holder member pivotally coupled to the first holder member, and fixedly coupled to the laser superstructure proximate the first side, and a flexible seal, wherein a portion of the flexible seal is coupled to the laser structure proximate the first side and disposed at least between the first holder member and the second holder member.
 2. The laser of claim 1 wherein the optical assembly includes an aperture extending at least partially therethrough, wherein the flexible seal is positioned within the aperture.
 3. The laser of claim 1 wherein the flexible seal includes a bellows.
 4. The laser of claim 1 wherein the second end portion of the thermal decoupler member is fixedly coupled to the laser superstructure proximate the second side.
 5. The laser of claim 1 wherein the optical assembly is a first optical assembly, and wherein the laser includes a second optical assembly fixedly coupled to the laser superstructure proximate the second side, and wherein the second end portion of the thermal decoupler member is fixedly coupled to the second optical assembly.
 6. The laser of claim 1 wherein the thermal decoupler member is a first thermal decoupler member, wherein the laser superstructure includes a second thermal decoupler member, and wherein the first and second thermal decoupler members extend along opposite sides of the laser superstructure.
 7. The laser of claim 1 wherein the thermal decoupler member includes an elongated rod.
 8. The laser of claim 1 wherein the laser superstructure includes a material having a first coefficient of thermal expansion (CTE), and wherein the thermal decoupler member includes a material have a second CTE that is less than the first CTE.
 9. The laser of claim 1 wherein the laser superstructure has a first side, a second side, and a sidewall extending therebetween, wherein the thermal decoupler member is spaced apart from the sidewall, and wherein the laser further comprises a thermal insulator between the sidewall and the thermal decoupler member.
 10. The laser of claim 1 wherein the first holder member has a first side and a second side opposite the first side, and wherein the optical assembly further includes: a first rotational joint proximate the first side; and a second rotational joint proximate the second side, wherein the first and second rotational joint define an axis about which the second holder member can pivot.
 11. The laser of claim 10 wherein each of the first and second rotational joints includes: a pivot element coupled to the first holder member; and a receptacle coupled to the second holder member and rotatably coupled to the pivot element.
 12. The laser of claim 10 wherein the optical assembly includes: a left side, a right side, a top side, and a bottom side; and a plurality of rotational joints, wherein the plurality of rotational joints includes a first rotational joint proximate the left side, a second rotational joint proximate the right side, a third rotational joint proximate the top side, and a fourth rotational joint proximate the bottom side, wherein the first and second rotational joints define a first axis about which the second holder member can pivot, and wherein the third and fourth rotational joints define a second axis about which the second holder member can pivot. 